The WHO today reported on 402 Saudi cases and on MERS-CoV transmission.

The World Health Organization (WHO) offered some new information today on 402 MERS-CoV cases reported in Saudi Arabia over the past 2 months, revealing that more than a quarter of the patients were healthcare workers, more than half of whom had mild symptoms or none at all.

In its latest MERS-CoV (Middle East respiratory syndrome coronavirus) summary, the WHO also said the general transmission pattern hasn't changed despite the surge of cases in April and early May. That suggests that a WHO emergency committee scheduled to meet on Jun 16 is unlikely to declare an international public health emergency.

Also today, single new MERS cases were reported in Saudi Arabia, the United Arab Emirates (UAE), and Iran. The UAE case involves a butcher who had camel contact, while the Iranian patient is a nurse assistant who had contact with Iran's first MERS patient.

The WHO today also released an update on animal-to-human transmission of MERS-CoV, reiterating that camels are a likely source of human infections and reemphasizing the need to beware of contact with the animals and their uncooked products.

Profile of 402 Saudi cases

The WHO summary report covers most of the Saudi cases reported during the recent hospital-outbreak-fueled upsurge. It does not include the 113 cases (and 92 deaths) that were retrospectively reported by Saudi Arabia on Jun 3; the agency said it is still investigating those cases with Saudi officials.

All but 12 of the 402 cases were included in previous WHO MERS notifications and case counts, but the agency hasn't provided details on them before. The agency's global MERS tally—which does not yet include the 113 Saudi cases reported Jun 3—is now 699 cases, with "at least" 209 deaths.

Of the 402 cases, 109 patients were healthcare workers, and 63 of them had mild or asymptomatic cases, the WHO reported. Another 35 had moderate illness that required hospitalization, 7 were severely ill, and 4 died.

The agency said most of the recent cases in Saudi Arabia resulted from human-to-human transmission in healthcare settings. In fact, it said, most of the cases initially classified as primary, meaning without links to other known cases, were later found to have involved contact with another case or exposure to a healthcare setting.

For the 402 patients overall, the median age was 46, and 58.3% of those with gender information were male. For the 398 patients with available information, 44.5% (177) were severely ill, which included 114 who died. Another 114 had no symptoms or were mildly sick. Information on preexisting conditions was available in only 149 cases; 140 of those patients had such conditions.

As for geography, the report confirms the central role of Jeddah and Riyadh in the recent outbreaks. There were 154 cases in Jeddah, 132 in Riyadh, 39 in Mecca, and 35 in Medina. Other affected sites were Tabuk, 10; Qunfudhah, 8; Al Taif, 7; Al Jawf, 6; Najran 3; and Ash Sharqiyah, 3. No location was specified for 5 cases.

Nationality was provided for 223 patients, of whom 138 were Saudi citizens, the WHO said.

Stable transmission pattern

Despite the flood of cases this spring, there has been no evidence of sustained community transmission of MERS-CoV, and the overall transmission pattern hasn't changed, the WHO said.

The main reasons for that conclusion: Secondary cases still tend to be milder than primary ones, exported cases have not sparked any sustained transmission, few instances of household transmission have turned up, and the number and size of household clusters has not increased.

The jury is still out on the key question of the role of asymptomatic cases in transmission, the report notes. Investigators in Saudi Arabia and the UAE are working on that, and one thing they have observed is that some individual who were initially asymptomatic later experienced mild symptoms.

Cases in UAE, Iran, Saudi Arabia

The WHO detailed the UAE and Iranian MERS cases in a statement e-mailed to journalists today. The agency was informed by the UAE on Jun 4 of an asymptomatic infection in a 36-year-old Abu Dhabi butcher who works in a slaughterhouse that processes camels and sheep.

He tested positive on May 20 in a general screening program for slaughterhouse workers, the WHO said. Now in isolation, the man had no contact with other MERS patients and no recent travel. No cases have been found in his contacts.

Iran reported its third MERS case to the WHO on Jun 4, the agency said. The patient is a 35-year-old nurse assistant who experienced mild symptoms on May 26. She was advised to stay home and take infection control precautions, and her symptoms abated on Jun 3.

She had close contact with Iran's first MERS case-patient, who was reported to the WHO May 26, the WHO said. Investigation of her contacts is ongoing.

The latest case in Saudi Arabia involves a 33-year-old Saudi man in Qunfudhah who has no symptoms and is in home isolation, the nation's Ministry of Health (MOH) said. He has no preexisting illness and does not work in healthcare.

The case raised the MOH's MERS count to 702 cases, while the death toll remained at 287.

Animal-to-human transmission

In its MERS-CoV summary and a separate statement on zoonotic transmission today, the WHO commented that recent studies "provide evidence that camels are a likely primary source of the MER-CoV that is infecting humans."

In particular, the agency said preliminary findings from an ongoing investigation in Qatar show that people who work closely with camels may be at higher risk for MERS-CoV infection than those who don't have frequent contact with camels. Meanwhile, a hunt for MERS-CoV antibodies in other animals has come up empty.

"The current pattern of disease appears to be the result of repeated introductions of the virus from camels to people, resulting in limited human-to-human transmission, but not in sustained transmission," the separate statement says.

As it has done before, the WHO recommends that anyone visiting places where camels are present should practice good hygiene measures, and people at risk for severe MERS disease should avoid camels, raw camel milk, camel urine, and camel meat that is not fully cooked. The agency also recommends that those who work with camels should wear facial protection and protective clothing.

In another e-mailed statement today, the WHO announced that the sixth meeting of its MERS-CoV Emergency Committee under the International Health Regulations will be held on Jun 16, with its findings likely to be announced Jun 17.

At the panel's last meeting on May 14, it concluded that the MERS-CoV situation did not meet the criteria for an international public health emergency.